Trichloroethylene (TCE), one of the most common groundwater pollutants, is a known hepatotoxin and carcinogen. It has been widely used by industry and the military as a solvent and degreaser. According to the Agency for Toxic Substances and Disease Registry, more than eight hundred Superfund sites in the United States are contaminated with TCE. Poplar, which can accumulate and degrade TCE, is an attractive plant for phytoremediation of TCE and other organic contaminants due to its high growth rate, extensive root system, high rates of water uptake from the soil, and ease of genetic manipulation. While transgenic poplar for improved TCE degradation has been successfully field tested, there are significant regulatory and breeding hurdles preventing the large-scale use of this technology. Recently, researchers have determined the potential of endophytes, symbiotic bacteria and fungi that live within plant cells, to break down organic contaminants and improve the phytoremediation capability of non-transgenic plants. Unlike other microbes that have been used for phytoremediation, endophytes live within the plant and therefore are expected to persist better at the site, continuing to degrade TCE as long as their plant partner survives. Dr. Sharon Doty, partner on the Phase I research and Phase II proposal, isolated a bacterial strain from poplar growing in sites contaminated with TCE and other organic pollutants that exhibited high rates of TCE degradation. Phase I results demonstrated the ability of this bacterial endophyte to persist in the roots of poplar trees and significantly enhance the degradation of TCE compared to control poplar. In Phase II, the field testing of this TCE bacterial endophyte will be accomplished at two TCE-contaminated sites for removal of TCE from groundwater compared to control poplar. In addition, the inclusion of a bacterial endophyte recently identified as a PAH degrader will also be tested in separate poplars and in those also inoculated with the TCE endophyte to determine the efficiency of this endophyte to degrade PAHs in the presence and absence of TCE. Because poplar is also a potential biomass energy crop, the potential use of the biomass for biopower or biofuel production following remedial activities will be investigated. Upon successful completion of this SBIR project, Edenspace will partner with Geosyntec, Inc., a leading environmental engineering firm, to introduce this novel technology to the remediation industry. PUBLIC HEALTH RELEVANCE: Trichloroethylene (TCE) is a known carcinogen and significant environmental contaminant as a result of extensive use by the military and industry. Poplar trees have been used as a natural method to remove TCE from contaminated groundwater. This NIH Phase II SBIR proposal seeks to continue development of poplars containing endophytes that are known degraders of TCE. Such endophytic poplars are expected to enhance TCE removal rates, thereby reducing exposure of TCE to humans and wildlife.